Cosmology with the submillimetre galaxies magnification bias: Proof of concept
Abstract
Context. As recently demonstrated, highz submillimetre galaxies (SMGs) are the perfect background sample for tracing the mass density profiles of galaxies and clusters (baryonic and dark matter) and their timeevolution through gravitational lensing. Their magnification bias, a weak gravitational lensing effect, is a powerful tool for constraining the free parameters of a halo occupation distribution (HOD) model and potentially also some of the main cosmological parameters.
Aims: The aim of this work is to test the capability of the magnification bias produced on highz SMGs as a cosmological probe. We exploit crosscorrelation data to constrain not only astrophysical parameters (M_{min}, M_{1}, and α), but also some of the cosmological ones (Ω_{m}, σ_{8}, and H_{0}) for this proof of concept.
Methods: The measured crosscorrelation function between a foreground sample of GAMA galaxies with spectroscopic redshifts in the range 0.2 < z < 0.8 and a background sample of HATLAS galaxies with photometric redshifts > 1.2 is modelled using the traditional halo model description that depends on HOD and cosmological parameters. These parameters are then estimated by performing a Markov chain Monte Carlo analysis using different sets of priors to test the robustness of the results and to study the performance of this novel observable with the current set of data.
Results: With our current results, Ω_{m} and H_{0} cannot be well constrained. However, we can set a lower limit of > 0.24 at 95% confidence level (CL) on Ω_{m} and we see a slight trend towards H_{0} > 70 values. For our constraints on σ_{8} we obtain only a tentative peak around 0.75, but an interesting upper limit of σ_{8} ≲ 1 at 95% CL. We also study the possibility to derive better constraints by imposing more restrictive priors on the astrophysical parameters.
 Publication:

Astronomy and Astrophysics
 Pub Date:
 July 2020
 DOI:
 10.1051/00046361/202038050
 arXiv:
 arXiv:2006.09185
 Bibcode:
 2020A&A...639A.128B
 Keywords:

 galaxies: highredshift;
 submillimeter: galaxies;
 gravitational lensing: weak;
 cosmological parameters;
 Astrophysics  Cosmology and Nongalactic Astrophysics
 EPrint:
 accepted in Astronomy &